JP2013002887A - Radiation detection panel and radiographic device - Google Patents

Abstract

A radiation detection panel for realizing a narrow frame is provided.
A radiation detection panel having a photoelectric conversion element for detecting fluorescence from a phosphor layer, the substrate having a photoelectric conversion element for supporting the phosphor layer, and a protective film covering the phosphor layer The phosphor layer is formed on the surface of the substrate and at least one side surface, and an angle formed by the surface and the at least one side surface is 90 degrees or less.
[Selection] Figure 1

Description

  The present invention relates to a radiation detection panel and a radiation imaging apparatus, and more particularly to a radiation detection panel and a radiation imaging apparatus that realize a narrow frame for mammography.

  The image characteristics of a digital radiation detection apparatus having an X-ray phosphor layer and a two-dimensional photodetector are good, and since the acquired data is digital data, the data is shared by importing it into a networked computer system. Therefore, research and development has been actively conducted on digital radiation detectors.

Among these digital radiation detection apparatuses, as a highly sensitive and sharp apparatus, a plurality of photo sensors and TFTs (Thin Film Transistors) and other electrical elements are arranged on a photodetector consisting of a photoelectric conversion element section arranged two-dimensionally. A radiation detection device is known that is formed by forming a phosphor layer for converting radiation into light that can be detected by a photosensor. An X-ray imaging device described in Patent Document 1 includes a photoelectric conversion element and a thin film transistor. A photoelectric conversion board configured by arranging a plurality of sets including two-dimensionally at substantially equal intervals, a drive processing circuit board for driving the photoelectric conversion board, and a signal processing for processing an output from the photoelectric conversion board The circuit board is configured to include a wavelength conversion member that converts X-rays into visible light. Here, the wavelength conversion member converts the X-ray distribution or X-ray image irradiated through the subject into a visible light distribution or a visible light image, and the photoelectric conversion substrate distributes the charge by photoelectric conversion of the visible light image. Or it converts into an electric signal. Further, the X-ray imaging apparatus includes a support member on which the photoelectric conversion substrate is placed, and either one of the drive processing circuit substrate and the signal processing circuit substrate is disposed on the opposite side of the photoelectric conversion substrate with respect to the support member. The photoelectric conversion substrate is disposed with an inclination of about 45 degrees with respect to the detection surface. Then, either one of the drive processing circuit board and the signal processing circuit board is arranged on the opposite side of the photoelectric conversion board with respect to the support member and substantially parallel to the detection surface of the photoelectric conversion board.

  In addition, in the radiation detection apparatus described in Patent Document 2, vapor deposition polymerization polyurea is used as a phosphor protective layer on the phosphor layer made of CsI: Tl having a columnar crystal structure, and vapor deposition polymerization polyurea is used as a reflection layer protection layer on the reflection layer. Is applied, and the end faces of both polyureas are formed thin toward the outside. By forming in this way, an attempt is made to obtain a structure that is strong against external stress at the formation end face. Both polyureas are also formed on the surface of the sensor panel opposite to the surface on which the phosphor layer is formed, and the end surfaces of the polyureas are also thinner outward. By forming in this manner, it is possible to obtain a sensor panel structure that functions as a cushioning material against external mechanical stress on the back surface of the sensor panel and has high impact resistance.

JP 2002-267758 A JP 2006-052983

  However, in Patent Document 1 and Patent Document 2, a narrow frame for the mammography FPD cassette cannot be realized. Here, the narrow frame means that an image can be formed up to an area having a small distance from one side of the cassette outline (for example, within 2 mm).

  In view of the above problems, an object of the present invention is to provide a radiation detection device (radiation detection panel) that realizes a narrow frame.

The radiation detection panel according to the present invention for achieving the above object is
A radiation detection panel having a photoelectric conversion element for detecting fluorescence by a phosphor layer,
A substrate for supporting the phosphor layer, having the photoelectric conversion element;
A protective film covering the phosphor layer,
The phosphor layer is formed on the surface of the substrate and at least one side surface, and an angle formed by the surface and the at least one side surface is 90 degrees or less.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation detection panel which implement | achieves a narrow frame can be provided.

(A) Typical top view of the radiation detection apparatus which concerns on 1st Embodiment, (b) Typical sectional drawing of the radiation detection apparatus which concerns on 1st Embodiment. Explanatory drawing of the manufacturing process of a radiation detection apparatus. Explanatory drawing of the manufacturing process of a radiation detection apparatus. Explanatory drawing of the manufacturing process of a radiation detection apparatus. The flowchart which shows the manufacture procedure of a radiation detection apparatus. The typical sectional view of the radiation detector concerning a 2nd embodiment. The typical sectional view of the radiation detector concerning a 3rd embodiment. The typical sectional view of those other than the chest wall side of the radiation detector concerning a 1st embodiment.

(First embodiment)
A radiation detection apparatus (also referred to as a radiation detection panel or a two-dimensional photodetector) according to a first embodiment will be described with reference to FIG. The radiation includes α rays, β rays, γ rays and the like in addition to X rays. FIG. 1A is a schematic plan view of the radiation detection apparatus, and FIG. 1B is a cross-sectional view taken along the line AA ′ in FIG.

  In FIG. 1B, a sensor panel 100 as a radiation detection apparatus includes a glass substrate 101, a photoelectric conversion element portion 102, a wiring portion 103, a contact lead 104, a protective layer 105, and a phosphor base layer 106. The antireflection layer 120 is provided.

  The glass substrate 101 is a base material that constitutes a basic portion of the radiation detection apparatus. The photoelectric conversion element unit 102 is composed of a photo sensor and TFT using amorphous silicon, for example. The wiring part 103 and the contact lead 104 are included in the photoelectric conversion element part 102.

  The protective layer 105 is made of, for example, silicon nitride, and in addition to SiN, TiO2, LiF, Al2O3, MgO, and the like, polyphenylene sulfide resin, fluorine resin, polyether ether ketone resin, liquid crystal polymer, polyether nitrile resin, polysulfone resin, polysulfone resin, and the like. Ether sulfone resin, polyarylate resin, polyamideimide resin, polyetherimide resin, polyimide resin, epoxy resin, silicon resin, or the like can be used. In particular, the protective layer 105 desirably exhibits a high transmittance at the wavelength of the light emitted from the phosphor because light converted by the phosphor passes through when irradiated with radiation.

  The phosphor base layer 106 is a base layer formed of a resin film or the like that also serves as a rigid protective layer of the photoelectric conversion element unit 102. The phosphor underlayer 106 may be any material as long as it can withstand a thermal process (200 ° C. or higher) in the phosphor layer forming step using the columnar phosphor. For example, a polyamideimide resin, a polyetherimide resin, a polyimide resin, an epoxy resin, a silicon resin, and the like can be given.

  The phosphor protective member 110 includes a phosphor protective layer 111, a reflective layer 112, and a protective base material 113. The phosphor protective member 110 has a function of moisture-proofing protection of the photoelectric conversion element portion 102 formed on the sensor panel 100 and a phosphor layer 114 described later, and is preferably composed of at least one material having a low moisture permeability.

  The phosphor protective layer 111 is made of an organic resin or the like, and bears adhesion between the phosphor protective member 110 and the phosphor layer 114. The phosphor protective layer 111 adheres and fixes the phosphor protective member 110 that covers the photoelectric conversion element portion 102 of the sensor panel 100 to the phosphor layer 114, and also protects the phosphor layer 114 and the photoelectric conversion element portion 102 from moisture. It is provided for the purpose. As the phosphor protective layer 111, a resin that has adhesiveness to other organic materials and inorganic materials in a heated and melted state and is in a solid state at room temperature and does not have adhesiveness may be used. Any material can be used as long as it meets this purpose, and a resin having a low moisture permeability is particularly preferable. Use a heat-curable adhesive that cures and cures when heated, for example, addition-reactive silicon, hot-cured acrylic or epoxy, and hot-melt resin (thermoplastic resin) such as polyolefin that can be plasticized and welded by heating. Can do. By forming the phosphor protective layer 111 made of this thermoplastic resin layer to be thicker than the phosphor layer 114 (not shown), the mechanical shock around the glass substrate 101 can be reduced.

  The material of the reflective layer 112 is preferably a metal with high reflectivity such as Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. The protective substrate 113 is a substrate for forming the reflective layer 112 in advance, and examples thereof include organic materials such as PET. The reflective layer 112 and the protective substrate 113 are used as a protective film.

  The phosphor layer 114 is a layer composed of a columnar phosphor. As the phosphor layer 114, an alkali halide activator is preferably used, and in addition to CsI: Tl, CsI: Na, NaI: Tl, LiI: Eu, KI: Tl, or the like can be used. The phosphor layer 114 is supported by the glass substrate 101 as a base.

  The antireflection layer 120 prevents the fluorescence from the upper surface (front surface) from being reflected by the side surface and the lower surface (back surface) of the glass substrate 101, and at the same time, the fluorescence from the phosphor layer 114 formed on the side surface of the glass substrate 101. It is prevented from entering the photoelectric conversion element portion 102 from the side surface.

  In the present embodiment, a case will be described in which a photoelectric conversion element portion 102 including a photosensor using amorphous silicon and a TFT is formed on a glass substrate 101 as a sensor panel 100 that is a two-dimensional photodetector. However, the present embodiment is not limited to this, and the same radiation detection can be performed by disposing an underlayer and a phosphor layer on a semiconductor single crystal substrate on which an image pickup device in which CCDs, CMOS sensors, etc. are two-dimensionally arranged is formed. A device can be configured. The same applies to other embodiments.

  A method for manufacturing the radiation detection apparatus described with reference to FIGS. 1A and 1B will be described. 2 (a) and 2 (b), FIG. 3 and FIG. 4 show the manufacturing process of the radiation detection apparatus. FIGS. 4A to 4 are schematic cross-sectional views taken along line AA ′ of FIG.

  FIG. 5 is a flowchart showing a manufacturing procedure of the radiation detection apparatus according to the present invention. First, in S501, as shown in FIG. 2A, on a semiconductor thin film made of amorphous silicon on a glass substrate 101, a photoelectric conversion element portion (photodetection element (pixel)) made of a photosensor and a TFT. 102 and the wiring part 103 are formed.

  In step S502, at least one side surface of the glass substrate 101 (for example, a chest wall side portion in contact with the chest of the patient) is cut. When cutting, cut out so that it inclines inward. That is, it cuts out so that the angle which the upper surface (surface) and side surface of the glass substrate 101 make may be 90 degrees or less.

  Cutting can be laser cutting or the like in addition to diamond cutting. Any cutting method may be cut so that the side surface is inclined toward the inner side of the glass substrate 101. The side surface of the glass substrate 101 is cut so as to be rougher than the upper surface. When diamond cutting is performed, it is easy to form a rough surface. By forming the rough surface, it is easy to prevent the phosphor from flowing through the side surface of the glass substrate 101 and adhering to the lower surface when the phosphor layer 114 is formed. Except for the chest wall side (AA ′ line) in FIG. This is because the entire radiation detection apparatus does not necessarily have a narrow frame. However, you may cut so that a side surface may incline other than a chest wall side (A-A 'line) with respect to the side surface to make a narrow frame.

  In step S <b> 503, a protective layer 105 made of SiNX and a phosphor base layer 106 obtained by curing polyimide resin are formed on the photoelectric conversion element unit 102 and the wiring unit 103.

  In S504, the antireflection layer 120 is further formed on the side surface and the lower surface of the glass substrate 101. By forming the antireflection layer 120, there is an effect of reducing a reduction in contrast of a radiographic image caused by fluorescence from the side surface entering the glass substrate 101.

  Next, in S505, as shown in FIG. 2 (b), a columnar crystallized phosphor made of an alkali halide (for example, CsI: Tl, thallium activated cesium iodide) as shown in FIG. 2B. A phosphor layer 114 made of is formed. The phosphor layer 114 is formed with a thickness of about 0.5 mm, and is formed on the phosphor base layer 106 so as to cover the upper surface of the photoelectric conversion element unit 102 that is two-dimensionally arranged. The phosphor layer 114 is formed on the surface side and side surface side of the glass substrate 101.

  In S506, thereafter, as shown in FIG. 3, the reflective layer of the film-like phosphor protective member 110 in which the Al film as the reflective layer 112 is formed on the protective substrate 113 made of PET having a thickness of 25 μm. A phosphor protective layer 111 made of a hot-mel type organic resin made of polyolefin resin is transferred and bonded to the surface on which 112 is formed using a heat roller (not shown).

  Next, in S507, the phosphor protective member 110 in which the phosphor protective layer 111 is formed on the phosphor layer 114 forming surface of the sensor panel 100 on which the phosphor layer 114 shown in FIG. It is pressed and adhered by a pressure roller (not shown). At this time, the stage (not shown) that holds the pressure roller and the sensor panel 100 is bonded without heating. In addition, the phosphor protective layer 111 made of hot melt resin is a thermoplastic resin, and in this embodiment, a resin having a melting point of about 100 ° C. is used. is there.

  Next, in S508, as shown in FIG. 4, the opposing surface of the phosphor protective layer 111 is heated and pressed against the sensor panel 100 using the line-shaped pressure head 140 incorporating the heater 130. Adhere. In the present embodiment, a pressure head 140 having a length capable of collectively pressing one of the peripheral sides of the phosphor protective member 110 is pressed and heated from above the phosphor protective member 110 and bonded to the other side sequentially. Are bonded in the same way. Note that the cushioning material 150 shown in FIG. 4 is for making the pressing force between the pressure head 140 and the surface of the sensor panel 100 uniform. For example, silicon rubber having a thickness of 0.3 mm is used. In this embodiment, the heater head temperature is controlled and adjusted so that the temperature of the phosphor protective layer 111 reaches 120 ° C., and heat-bonded for 10 seconds. In this way, the radiation detection apparatus as shown in FIG. 1 according to this embodiment is manufactured.

  It should be noted that each layer (film) constituting the radiation detection panel described in the present embodiment does not necessarily have to include all, and the combination thereof may be arbitrary. Further, the protective substrate 113 and the reflective layer 112 as protective films covering the phosphor layer 114 may be configured to cover the front surface side and the side surface side of the glass substrate 101, and may be configured to cover the back side. Good.

  FIG. 8 shows a cross section taken along line B-B ′ of FIG. In the mammography FPD cassette, the three side surfaces other than the chest wall side are configured in a cross section as shown in FIG. 8 without performing the processing of the present embodiment. The present invention is applicable to at least one side surface, and may be applied to three side surfaces other than the chest wall side.

  As described above, the phosphor can be used as a buffer material against destruction of the film (phosphor protective film) disposed on the side. Further, since the photoelectric conversion element can be disposed up to the periphery of the glass substrate (for example, within 2 mm from the end), a narrow frame can be realized at low cost. This is applicable to both direct and indirect deposition. By using the radiation imaging apparatus including the radiation detection apparatus according to the present invention, a narrow frame radiation image can be obtained.

(Second Embodiment)
As shown in FIG. 6, the present embodiment is different from the first embodiment in the formation method of the antireflection layer 120 in S <b> 504. Specifically, the difference is that the antireflection layer 120 is formed not only on the side surface and the lower surface of the glass substrate 101 but also on the upper surface of the glass substrate 101. An antireflection layer 120 is formed on the periphery of the upper surface of the glass substrate 101 with a width of about 0.5 mm to 1 mm. That is, the antireflection layer 120 is formed between the phosphor layer 114 and the glass substrate 101 even in a predetermined region from the boundary with the side surface on the surface of the glass substrate 101.

  By forming the antireflection layer 120 also on the periphery of the upper surface of the glass substrate 101, the thickness of the phosphor layer 114 can be controlled. By forming the antireflection layer 120 on the upper surface, it is possible to suppress a decrease in the thickness of the phosphor layer 114 in the peripheral portion of the upper surface of the glass substrate 101.

(Third embodiment)
In the present embodiment, as shown in FIG. 7, the material of the photoelectric conversion element unit 102 is different from that of the first embodiment. In the first embodiment, the case where the photoelectric conversion element unit 102 including the photosensor using amorphous silicon and the TFT is formed on the glass substrate 101 has been described. However, the photoelectric conversion element unit 102 is not an amorphous silicon but a crystal. It is assumed that silicon is used.

  An example of the photoelectric conversion element unit 102 according to this embodiment is a CMOS sensor. Since the CMOS sensor has conductivity, it needs to be insulated when it is attached to the support member 107. In the case of the third embodiment, a silicon substrate 160 is used as a base material instead of the glass substrate 101, an insulating protective layer 105 is formed as an insulating layer on the upper surface of the silicon substrate 160, and a phosphor underlayer is further formed on the upper surface. 106 is formed. Others are manufactured by the same method as in the first embodiment.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (8)

A radiation detection panel having a photoelectric conversion element for detecting fluorescence by a phosphor layer,
A substrate for supporting the phosphor layer, having the photoelectric conversion element;
A protective film covering the phosphor layer,
The phosphor layer is formed on the surface of the substrate and at least one side surface, and an angle formed by the surface and the at least one side surface is 90 degrees or less.   The radiation detection panel according to claim 1, wherein the protective film is formed on the back surface of the base material so as to cover the phosphor layer.   The radiation detection panel according to claim 1, wherein the side surface is formed as a surface rougher than the surface.   The radiation detection panel according to any one of claims 1 to 3, wherein an antireflection layer is further formed between the phosphor layer and the base material on the side surface.   The said antireflection layer is further formed between the said fluorescent substance layer and the said base material in a predetermined area | region from the boundary part with the said side surface in the surface of the said base material. Radiation detection panel.   The radiation detection panel according to claim 1, wherein the base material is formed of silicon, and an insulating layer is formed on a surface of the base material.   The thermoplastic resin layer is formed between the phosphor layer and the protective film, and the thermoplastic resin layer is formed thicker than the phosphor layer on the side surface of the substrate. The radiation detection panel according to any one of 1 to 6.   A radiation imaging apparatus comprising the radiation detection panel according to claim 1.